JP3153441B2 - Surface burning burner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface combustion burner used in various combustion devices such as a water heater.

[0002]

2. Description of the Related Art Conventionally, as a surface combustion burner used for various combustion devices such as a water heater, a combustion plate is attached so as to cover one surface of a gas burner main body, and gas ejected from the combustion plate is used for the combustion plate. There is known a configuration in which combustion occurs on the surface of an object.

In recent years, it has been studied to use a compact obtained by laminating silicon carbide-coated Si—CO—based silicon carbide fibers on the combustion plate. As the silicon carbide fibers, SiC _1.20 O _0.42 SiC-O type silicon carbide fiber having a composition of (Nippon Carbon Co., Ltd., Nicalon (trademark)) is known. This fiber is a flexible continuous filament yarn which is susceptible to pyrolysis itself, but which can be chemically vapor deposited (abbreviated as CVD) or chemical vapor infiltration (Chemical VaporInf).
illumination, abbreviated as CVI method)
By coating the surface with silicon carbide, excellent heat resistance can be obtained.

[0004] However, when silicon carbide is coated by the CVD method or the CVI method on the whole formed body having a predetermined thickness obtained by laminating Si-CO-based silicon carbide fibers, the heat resistance of the front and back sides is increased. It has been found that different compacts can be obtained. Therefore, it is desired to attach the molded body to the gas burner body such that the surface having excellent heat resistance becomes the combustion surface of the combustion plate.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has an excellent combustion surface of a combustion plate formed by laminating Si-CO-based silicon carbide fibers coated with silicon carbide. Provided is a surface combustion burner capable of obtaining improved heat resistance.

[0006]

Means for Solving the Problems When coating a silicon carbide (SiC) by a CVD method or a CVI method on a molded body formed by laminating Si-CO-based silicon carbide fibers, heating is performed to about 1200 to 1300 ° C. 20 to 60
The compact is horizontally placed in a low-pressure furnace of about Torr, and a carrier gas containing a reaction material gas such as SiCl ₄ and CH ₄ is allowed to flow down from above the compact vertically to form the compact. Si on the surface of the fiber forming the body
C is deposited to form a SiC coating. According to the study of the present inventors, a formed body having a predetermined thickness obtained by laminating the Si-CO-based silicon carbide fibers by the CVD method or the CVI method is entirely coated in the thickness direction. When coated with SiC over the surface, under the influence of gravity, the thickness of the SiC coating is reduced on the surface of the molded body facing the airflow, and the thickness of the SiC coating is increased on the opposite surface. There was found. In the Si-CO-based silicon carbide fiber coated with SiC, the thickness of the SiC coating is 0.1 to 0.7.
When the thickness is in the range of μm, heat resistance is exhibited at a temperature of 1300 to 1400 ° C., but when the thickness of the SiC film exceeds 0.7 μm, it is easily deteriorated by heat of about 800 to 1000 ° C.

To eliminate the effect of gravity, the CV
It is conceivable that the D method or the CVI method is performed under a high vacuum, but an increase in cost is inevitable to obtain a high vacuum.

Therefore, the surface burning burner of the present invention is made of Si
-A molded body obtained by laminating CO-based silicon carbide fibers,
At the time of the coating, a combustion plate formed by coating a silicon carbide film by depositing silicon carbide on the surface of the fiber while facing a gas flow containing the raw material gas for reaction under high temperature and low pressure, The gas burner body is attached so as to cover one surface of the gas burner main body with the surface on the side facing the air current containing the combustion surface as a combustion surface.

[0009]

According to the surface burning burner of the present invention, Si-C-
The molded body obtained by laminating the O-based silicon carbide fibers is placed on a gas burner body such that the surface coated with silicon carbide becomes a combustion surface in opposition to an air current containing a raw material gas for reaction under high temperature and low pressure. Since it is attached, the surface of the thinner SiC film formed by the coating becomes the combustion surface.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a surface combustion burner according to the present invention. FIG. 1 is a perspective view showing a configuration of a surface combustion burner of the present embodiment, FIG. 2 is an end view taken along line II-II of FIG. 1, and FIG. 3 is an explanatory sectional view showing a method of coating silicon carbide.

The surface burning burner of this embodiment is used in a rear exhaust type combustion device for cooking grilled fish such as grilled fish, which is generally called a grill, and is mounted on a ceiling of a combustion chamber in which a material to be burned is placed. And a burner for the upper fire, which is disposed so as to face the above-mentioned fired material. As shown in FIG. 1, the surface combustion burner 1 of the present embodiment is a flat box-type having a gas mixing pipe 2 for mixing a gas ejected from a nozzle (not shown) and primary air to supply a gas mixture. Si coated with silicon carbide so as to cover one surface of the gas burner main body 3 of FIG.
Combustion plate 4 formed by laminating CO-based silicon carbide fibers
However, at the time of the coating, the surface facing the airflow containing the raw material gas for reaction is attached as a combustion surface. In the surface combustion burner 1, as shown in FIG. 2, a gap between the gas burner main body 3 and the combustion plate 4 forms a gas passage 5 for flowing a gas mixture supplied from a gas mixing pipe 2. The combustion plate 4 is provided with a large number of small-diameter flame ports 6 that penetrate the combustion plate 4 to eject and burn the gas mixture. In the surface combustion burner of the present embodiment, the main combustion flame is formed mainly by the combustion of the gas mixture ejected from the flame port 6, and
Even in the portion where the flame opening 6 is not provided, a small flame is formed by the secondary combustion of the gas mixture ejected from the gap between the fibers.

The combustion plate 4 has a diameter of 9 to 25 μm.
m, a binder such as water, a ceramic adhesive, a synthetic resin adhesive [for example, polyvinyl alcohol (PVA)], or a Si—CO—based silicon carbide fiber having a density of 2.0 to 3.0 g / cm ³ as it is. , Impregnated, and filled in a mold having a predetermined shape, and then pressed to a thickness of 1.5 to 6.
A molded article having a thickness of 0 mm was formed, and the molded article was coated with silicon carbide by the CVD method to form a SiC coating on the surface of the fiber.

The flame port 6 is formed by a method of performing a drilling or punching process on the molded body, and using a mold having a projection of the shape of the flame port at a portion where the flame port is provided when forming the molded body. After laminating (by a papermaking method) the above-mentioned Si-CO-based silicon carbide fiber in the mold, filling and pressing,
The projections are formed by a method of removing the mold together with the projections. In addition, since the combustion flame is formed by the gas mixture ejected from the gap between the fibers in the molded body as described above, the flame port 6 may not be provided.

In the above-mentioned CVD method, as shown in FIG. 3, a compact 7 obtained by laminating Si-CO-based silicon carbide fibers is placed horizontally in a CVD furnace under high temperature and low pressure. The flow is performed by flowing down a gas stream 8 of a carrier gas (H ₂ ) containing raw material gases for reaction (SiCl ₄ and CH ₄ ) from vertically above the body 7. The CVD furnace is heated to a temperature in the range of 1200-1300 ° C. and depressurized to a pressure in the range of 20-60 Torr. When the treatment is performed for 5 to 30 minutes under the high-temperature and low-pressure conditions, the surface of the Si—CO—based silicon carbide fiber on the surface 7 a of the molded body 7 facing the airflow 8 has a thickness of 0.1 to 0.7 μm. On the opposite face 7b, the surface of the fiber is coated with a thicker SiC coating than the face 7a under the influence of gravity.

Although the surface 7a of the molded body 7 has heat resistance at a temperature of 1300 to 1400 ° C. due to the SiC coating having the above thickness, the surface 7b of the molded body 7 is easily deteriorated by heat of about 800 to 1000 ° C. I do. Therefore, the combustion plate 4 is shown in FIG.
As shown, the molded body 7 is attached to the gas burner main body 3 such that the surface 7a of the molded body 7 becomes a combustion surface. Note that the combustion plate 4 is formed by laminating the Si-CO-based silicon carbide fibers, and the fibers are in point contact with each other.
The thermal conductivity of the molded body 7 as a whole is low, and the surface 7 of the molded body 7
There is no fear that b is heated to 800 ° C. or higher.

In the above embodiment, the coating of the molded body 7 is performed by the CVD method, but may be performed by the CVI method. Further, in the embodiment, the surface combustion burner used in the back-exhaust type combustion device for grilled ware is described, but the surface combustion burner of the present invention is not limited to this, and various combustion such as a water heater can be used. Can be used for equipment.

[0017]

As is apparent from the above, according to the surface burning burner of the present invention, the burning surface of the burning plate formed by laminating Si-CO-based silicon carbide fibers coated with silicon carbide is excellent. Heat resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a surface combustion burner according to an embodiment.

FIG. 2 is an end view taken along line II-II of FIG.

FIG. 3 is an explanatory sectional view showing a method for coating silicon carbide.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Surface combustion burner, 3 ... Gas burner main body, 4 ... Combustion plate, 7a ... Surface facing the airflow containing reaction raw material gas, 8 ... Airflow containing reaction raw material gas.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F23D 14/12-14/18

Claims (1)

(57) [Claims] 1. A molded body obtained by laminating Si—CO—based silicon carbide fibers is opposed to an air flow containing a raw material gas for reaction under high temperature and low pressure to precipitate silicon carbide on the surface of the fibers. A combustion plate formed by coating with a silicon carbide film is attached so as to cover one surface of the gas burner main body with a surface facing a gas flow containing the reaction raw material gas as a combustion surface during the coating. A surface-burning burner, characterized in that: